Ankle Joint Replacement

Introduction

Ankle joint replacement surgery also known as total ankle arthroplasty is a surgical treatment option for patients bothered by pain and loss of range of motion of their ankle joint. Your doctor may recommend this procedure if conservative treatment options such as medications and injections have failed to alleviate your symptoms.

In order to better understand the ankle joint replacement procedure, it is important to know the normal anatomy of the ankle joint.

Normal Ankle Joint Anatomy

Three bones join to form the ankle joint. They include the shin bone or the tibia, the thinner bone going along the tibia known as the fibula, and the foot bone located above the heel bone known as the talus.

The bony protrusions seen and felt over the ankle joint are the malleolus. These include the medial malleolus which forms the base of the tibia and is felt on the inside of the ankle, the posterior malleolus which also forms the base of the tibia and is felt on the back of the ankle, and the lateral malleolus which is the low end of the fibula and is felt on the outside of the ankle.

The ankle joint allows up-and-down motion of the foot and the subtalar joint, located below the ankle joint, allows side-to-side motion of the foot. Bands of tough fibrous tissue known as ligaments surround the ankle joint and subtalar joints attaching the bones of the leg to each other and to the bones of the foot.

Causes

Arthritis is one of the major causes for ankle joint replacement. Arthritis is a general term covering numerous conditions where the joint surfaces wear out. The joint surface is covered by a smooth articular surface made of cartilage that allows pain free movement in the joint. This surface can wear out for a number of reasons. Often the definite cause is unknown. When the articular cartilage wears out, the bone ends rub on one another causing pain.

In an arthritic ankle joint the cartilage lining is either thinner than normal or absent, the joint capsule is swollen, the joint space is narrowed, and bone spurs or excessive bone growth may occur at edges of the joint.

Magnetic Resonance Imaging (MRI) – Magnetic and radio waves are used to create a computer image of soft tissue such as nerves and ligaments.

Surgical procedure

Ankle joint replacement surgery is performed under sterile conditions in the operating room. It is often performed under general anesthesia, which means you will be asleep and will feel no pain throughout the procedure. Depending on your condition, you may be instead given a spinal anesthesia, where you will be numbed below your waist and will be awake throughout the procedure, along with medication to help you relax during your procedure. Your surgeon will then make a small cut in front of your ankle and expose the ankle joint. Care will be taken to protect tissues and neurovascular structures and they will be pulled back from the site of the operation using retractors. Your surgeon will then use a bone saw to cut and remove damaged bone and cartilage from the tibia and talus.

Under the guidance of C-arm fluoroscopy (live-action x-rays), special surgical instruments are then used to cut the talus and tibia to precisely accommodate the new metal prostheses. The new metal parts of the artificial joint are then appropriately attached to the prepared bony surfaces of the talus and the tibia. Special glue or bone cement may be used to hold them in position. A plastic prosthesis is then inserted between the two metal parts. It acts like an artificial cartilage and prevents the metal parts from rubbing against each other. The tendons and neurovascular structures are then positioned back to their normal anatomical position. In some cases, a plastic tube known as a drain will be placed in the surgical wound to drain any fluid. The surgical wound is then closed with sutures. Bandages are applied and the ankle is then immobilized using a splint, cast, or brace.

Post-Operative Care

You may need to stay in the hospital at least one night after your surgery. Your ankle will be in a cast or a splint.

You will be given pain medicines to control your postoperative pain.

Drain tube, if any, will be removed after 1 or 2 days.

Your ankle will be elevated on a pillow above the level of your heart and ice packs may be applied over the dressing to help reduce swelling and discomfort.

Physical Therapy (PT) will begin soon after surgery and you will be instructed on special exercises to help you regain full range of motion of your ankle joint.

Sutures will usually be removed after 10-14 days.

You will be instructed to keep your incision site clean and dry. You will be allowed to shower once the dressings are removed unless otherwise directed by your surgeon.

You will be given specific instructions regarding activity and rehabilitation.

Eating a healthy diet and not smoking will promote healing.

Advantages & Disadvantages

Most patients are benefited with preservation of their existing range of motion after a successful ankle joint replacement surgery. The survival of this procedure depends on the wear of the artificial joint and a revision surgery may be recommended in the future. Total ankle replacement may last for 10 or more years and the longevity depends on the extent of damage on the ankle joint before surgery, your overall health, and your activity levels.

Risks and complications

Complications can be medical (general) or specific to ankle surgery. Medical complications include those of the anesthetic and your general wellbeing. Complications include: